From ea043f76c5e9d696bc10d7c3bfc3e2dcf688e32b Mon Sep 17 00:00:00 2001
From: George Norton <george_norton_uk@hotmail.com>
Date: Wed, 23 Aug 2023 00:37:11 +0100
Subject: [PATCH] Replace a few doubles with floats. According to the
 raspberry-pi-pico-c-sdk manual, doubles are around 3 times slower than
 floats.

---
 firmware/code/configuration_manager.c | 6 +++---
 firmware/code/fix16.h                 | 2 ++
 firmware/code/fix16.inl               | 6 ++++++
 firmware/code/run.c                   | 1 +
 4 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/firmware/code/configuration_manager.c b/firmware/code/configuration_manager.c
index 3f35faa..e17728a 100644
--- a/firmware/code/configuration_manager.c
+++ b/firmware/code/configuration_manager.c
@@ -136,7 +136,7 @@ bool validate_filter_configuration(filter_configuration_tlv *filters)
                 printf("Error! Not enough data left for filter6 (%d)\n", remaining);
                 return false;
             }
-            if (args->a0 == 0.0) {
+            if (args->a0 == 0.0f) {
                 printf("Error! The a0 co-efficient of an IIR filter must not be 0.\n");
                 return false;
             }
@@ -189,7 +189,7 @@ void apply_filter_configuration(filter_configuration_tlv *filters) {
                 uint32_t checksum = 0;
                 for (int i = 0; i < sizeof(filter6) / 4; i++) checksum ^= ((uint32_t*) args)[i];
                 if (checksum != bqf_filter_checksum[filter_stages]) {
-                    bqf_filters_left[filter_stages].a0 = fix3_28_from_dbl(1.0);
+                    bqf_filters_left[filter_stages].a0 = fix16_one;
                     bqf_filters_left[filter_stages].a1 = fix3_28_from_dbl(args->a1/args->a0);
                     bqf_filters_left[filter_stages].a2 = fix3_28_from_dbl(args->a2/args->a0);
                     bqf_filters_left[filter_stages].b0 = fix3_28_from_dbl(args->b0/args->a0);
@@ -315,7 +315,7 @@ bool apply_configuration(tlv_header *config) {
 #ifndef TEST_TARGET
             case PREPROCESSING_CONFIGURATION: {
                 preprocessing_configuration_tlv* preprocessing_config = (preprocessing_configuration_tlv*) tlv;
-                preprocessing.preamp = fix3_28_from_dbl(1.0 + preprocessing_config->preamp);
+                preprocessing.preamp = fix3_28_from_flt(1.0f + preprocessing_config->preamp);
                 preprocessing.reverse_stereo = preprocessing_config->reverse_stereo;
                 break;
             }
diff --git a/firmware/code/fix16.h b/firmware/code/fix16.h
index 9d7887e..66799ad 100644
--- a/firmware/code/fix16.h
+++ b/firmware/code/fix16.h
@@ -43,6 +43,8 @@ static inline fix3_28_t norm_fix3_28_from_s16sample(int16_t);
 
 static inline int16_t norm_fix3_28_to_s16sample(fix3_28_t);
 
+static inline fix3_28_t fix3_28_from_flt(float);
+
 static inline fix3_28_t fix3_28_from_dbl(double);
 
 static inline fix3_28_t fix16_mul(fix3_28_t, fix3_28_t);
diff --git a/firmware/code/fix16.inl b/firmware/code/fix16.inl
index 91a1aa6..ca45a2e 100644
--- a/firmware/code/fix16.inl
+++ b/firmware/code/fix16.inl
@@ -74,6 +74,12 @@ static inline int16_t norm_fix3_28_to_s16sample(fix3_28_t a) {
     return (a >> 12);
 }
 
+static inline fix3_28_t fix3_28_from_flt(float a) {
+    float temp = a * fix16_one;
+    temp += ((temp >= 0) ? 0.5f : -0.5f);
+    return (fix3_28_t)temp;
+}
+
 static inline fix3_28_t fix3_28_from_dbl(double a) {
     double temp = a * fix16_one;
     temp += (double)((temp >= 0) ? 0.5f : -0.5f);
diff --git a/firmware/code/run.c b/firmware/code/run.c
index f399126..3a33f89 100644
--- a/firmware/code/run.c
+++ b/firmware/code/run.c
@@ -291,6 +291,7 @@ void setup() {
  * IF YOU DO, YOU COULD BLOW UP YOUR HARDWARE!                               *
  * YOU WERE WARNED!!!!!!!!!!!!!!!!                                           *
  ****************************************************************************/
+ // TODO: roundf will be much faster than round, but it might mess with timings
 void configure_neg_switch_pwm() {
     gpio_set_function(NEG_SWITCH_PWM_PIN, GPIO_FUNC_PWM);
     uint slice_num = pwm_gpio_to_slice_num(NEG_SWITCH_PWM_PIN);